Case Study of Earthquake Probability Using Natural Time and Nowcasting of the Sarpol-e Zahab Region in Kermanshah, Iran

Abstract

The observed statistical seismic quantity is critical to understanding the nature of earthquakes and potential hazards in earthquake-prone areas. We have studied the nowcasting concept, which examines the current uncertain situation of earthquake risk assessment in Sarpol-e Zahab and the surrounding areas. In order to evaluate the statistical distribution of the interevent counts of small events that occur between large events, we used the natural time concept rather than clock time. The earthquake potential score (EPS) was calculated as the total number of small earthquakes after the last large occurrence in the studied area. We have determined the EPS values to consider events of M ≥ 4.4 within two different radius (250 and 350 km) around the city center studied. The EPS values for Sarpol-e Zahab at 250 km corresponding to M ≥ 5.5 and six events found to be almost 0.86 and 0.97, respectively, while at 350 km these values are equal to 0.73 and 0.50 for M ≥ 5.5 and six events, respectively.